Response shaping by multiple injection in a ring-type structure

ABSTRACT

Structures for response shaping in frequency and time domain, include an optical response shaper and/or a modulator device with multiple injection. The device comprises a resonator having an enclosed geometric structure, for example a ring or racetrack structure, at least two injecting optical waveguides approaching the resonator to define at least two coupling regions between the resonator and the injecting waveguides, and may define at least two Free Spectral Range states. 
     One or both of the coupling regions has a coupling coefficient selected for a predetermined frequency or time response, and the coupling coefficient or other device parameters may be variable, in some case in real time to render the response programmably variable.

RELATED APPLICATION(S)

This application claims the benefit of priority under 35 USC § 119(e) ofU.S. Provisional Patent Application No. 62/764,780 filed on Aug. 16,2018, the contents of which are incorporated by reference as if fullyset forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to aring-type resonator using double or multiple optical signal injectionports or coupling regions.

As the field of integrated optics expands, small size silicon-basedmodulators and filters have been studied and demonstrated, consequentlymotivating further exploration at both the transmitter and receiversides. In many applications, specific frequency, or electrical responsesare desired. In Radio Frequency (RF) applications, linear transmissionis typically required in order to provide a large Spur-Free DynamicRange (SFDR). Detecting digitally modulated optical signals requires anoptical comparator that can be realized by a device having a square waveshape. A square-like behavior, this time in the frequency domain, isalso encountered when considering a bandpass box-like filter in highcapacity optical links such as Wavelength-Division Multiplexing (WDM).WDM-based devices are used in Dense WDM (DWDM) systems viamultiplexing/de-multiplexing odd and even channels by employing aso-called interleaver filter. The separation of channels, obtained bythe interleaved shaped waveform, is also needed to facilitate trafficrouting within a relay station.

Response shapes, being output waveforms in both frequency and timedomain, are commonly realized by complex optical circuits oftencomprising several optical elements. In the case of analog RFapplications, a chain of Mach-Zehnder Interferometers (MZI) was requiredto obtain high SFDR; Ring-Assisted MZI (RAMZI) with multiple electrodeshave also been widely explored. Several complex designs were suggestedfor detecting digitally modulated optical signals by using an opticalcomparator. These designs require multiple electrodes and largefootprint. To obtain a sharp box-like filter response, five cascadedrings were devised while several rings coupled to a MZI were reported.For an interleaver, a flat-top spectral response is required orotherwise the transmission efficiency will be sensitive to a slightshift in wavelength (e.g. laser quality, temperature). Consequently, thesinusoidal response of a single unbalanced cross-bar MZI is notadequate. This motivated the analysis of circuits comprising MZIs in aserial configuration made of directional couplers (DC) or MultimodeInterferometers (MMI) elements to obtain a flat-top response. Aninterleaver for Nyquist-WDM (super-channel) based on RAMZI circuits withadditional coupled rings has recently been demonstrated. Theabovementioned solutions exhibit similar characteristics such as largefootprint, fabrication sensitivity and multiplicity of electrodes.

Large Free Spectral Range (FSR) is required for various circumstances.These include some sensing applications, tunable filters, and WDMarchitecture where large FSR is required to encompass a large frequencyrange or avoid cross-talk among channels. FSR increase is typicallyachieved by reducing the resonator length, however, this also reducesthe electrode length, consequently increasing the required operatingvoltage. Small size optical structures, such as photonic crystals andrather complex ring resonator-based designs, have been suggested toincrease the FSR and may, in theory, be able to operate under lowvoltage. These, however, are more complicated to fabricate and harder tointegrate with an electrical control.

Optical circuits based on ring resonators are very sensitive tofabrication deviations. A small variation in the coupling or losscoefficients may drastically decrease the Extinction Ratio (ER) of thetransmission. A 3D Finite Difference (FDTD) sensitivity analysis showedthat for about 20 nm (i.e. 5% in silicon) deviation in waveguide width,the power coupling ratio can vary by more than 20%; while the generalshape of the transmission is preserved, the ER then decreases by morethan 15 dB. Such deviations significantly impact large circuits withmore than one optical element, and may burden the yield in massproduction. A less sensitive device is the MZI. However, due to powersplitting variances, undersigned variations in length (imbalance)between its arms, and width deviations, the MZI cannot provide infiniteER, but typically yields 15-30 dB of extinction.

In a recent publication, a racetrack-shaped ring resonator augmented bya Double Injection (DI) configuration was presented. It was aimed atproviding a modulator having finer linear voltage-transmission response,and this was achieved by placing an electrode over the racetrack. Thedevice is herein abbreviated FLAME.

SUMMARY OF THE INVENTION

The present embodiments are based on coupling optical fields intoring-type structures at two or more ports and/or two or more couplinglocations, where it was discovered that the FLAME device as disclosed inthe background allows response shaping of the output signal in a varietyof waveforms both in frequency and time domain. In embodiments, theresponse shaping is programmable. Response shaping may be attained bydetermining the value of the coupling coefficients or of variousparameters of the waveguides via a diversity of mechanisms, includingstatic and dynamic mechanisms.

According to an aspect of some embodiments of the present inventionthere is provided an optical response shaper and/or a modulator devicewith multiple injection, the device comprising:

a resonator having an enclosed geometric structure;

at least two injection optical waveguides between an input port and asecond end, the optical waveguides passing the resonator at respectiveapproach points;

coupling regions between the resonator and the injecting waveguides atthe approach points respectively, the coupling regions providing opticalcoupling between the resonator and the injecting waveguides, therebydefining at least two Free Spectral Range states; and

at least one output port at a second end of at least one of theinjection optical waveguides for providing a predetermined frequency ortime or phase response

In embodiments, the free spectral range states comprise a first,regular, state and at least one more, larger period state.

In embodiments, at least one of the two coupling regions is configuredwith a coupling coefficient selected for the predetermined frequency ortime or phase response.

Embodiments may comprise at least one electrode placed close to or overat least one of the coupling regions, the electrode being forprogrammably altering a respective coupling coefficient to vary thepredetermined frequency response or time response.

Embodiments may comprise an electrode close to or over each couplingregion respectively, thereby to alter coupling coefficients at eachcoupling region.

Embodiments may comprise an electrode close to or over non-couplingregions of the resonators, thereby to alter the FSR or other parametervalues of the device.

Embodiments may comprise one input port and a y-coupler to each of theinjection waveguides.

Alternatively, each of the at least two injection waveguides comprises arespective independent input port. One port may receive a control signaland the other may receive a reference signal.

In embodiments, a length along a first of the injection waveguides froma respective input port to a respective coupling region is differentfrom a length of a second of the injection waveguides from a respectiveinput port to a respective coupling region.

In embodiments, the enclosed geometric structure comprises a ringstructure or a racetrack structure.

Embodiments may comprise an electrode in vicinity of one of the couplingregions, the electrode comprising one member of the group comprising aPN diode, PIN diode, MOS capacitor, and a BJT transistor. Alternatively,a modulating electrode based on thermo-optic or electro-optic (Pockels)effect may be used.

Embodiments may comprise an electrical element in the vicinity of atleast one of the waveguides.

The predetermined response may be any of sinusoidal, triangular, square,combined dips and peaks, spikes, an interleaver, a fano-spectrum shapeand a Parameters-Insensitive-Response. Indeed suitable setting of theparameters of the device may be found for any reasonable responseoutput.

In embodiments, the coupling coefficient is at least partly governed bya distance between the resonator and a respective waveguide, or thewaveguides' width, at a respective coupling region.

Devices according to the present embodiments may provide a constellationof points for quadrature amplitude modulation (QAM), or devices mayprovide modulations consisting of: Phase Shift Keying (PSK), PulseAmplitude Modulation (PAM), Quadrature Amplitude Modulation (QAM) andAmplitude and Phase Shift Keying (APSK).

In embodiments, the field or intensity of the signal in time orfrequency or phase domains is affected by an optical input power,delivered via one of the injecting waveguides.

Devices according to the present embodiments may include only oneresonator and/or only one operating electrode for operating resonance inthe device.

Embodiments may provide a field programmable optical array comprisingoptical devices as discussed herein connected together into a grid.

According to a second aspect of the present invention there is provideda field programmable optical array or a photonic processor comprisingoptical devices as described herein connected together into a grid.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 is a simplified diagram showing an optical device according to afirst embodiment of the present invention and showing coupling regionswhere coupling coefficients are set to provide predetermined responses;

FIG. 2A-J is a simplified diagram showing ten exemplary predeterminedresponses that can be achieved by suitable setting of the couplingcoefficients in the coupling regions of FIG. 1;

FIGS. 3A-3C are three graphs illustrating the parameter insensitiveresponse of a device according to the present embodiments;

FIG. 4A-J shows a scanning electron microscope (SEM) image and spectralresponses (E_(t1)) of optical circuits using the device of FIG. 1;

FIG. 5A is a view of the trapezoidal cross-section for the parallelsection of a device according to the present embodiments;

FIG. 5B is an illustration of the structure of a device according to thepresent embodiments, simulated in the software to analyze the ring/inputcouplers;

FIG. 5C is a simulated coupling coefficient as a function of the gapbetween the bus and ring waveguides (κ→power coupled to the ring);

FIG. 5D is a dispersion of a coupler for various lengths of parallelsection;

FIG. 6 is a simplified schematic diagram of a double injection deviceaccording to the present embodiments;

FIG. 7 is a simplified schematic diagram of an alternative doubleinjection device according to the present embodiments;

FIG. 8 is a simplified schematic diagram of a further alternative of adouble injection device according to the present embodiments;

FIG. 9 is a simplified schematic diagram of a yet further alternative ofa double injection device according to the present embodiments;

FIGS. 10A-10C are diagrams of a yet further double injection device andgraphs showing its use for QAM;

FIG. 11 is a simplified diagram showing how multiple double injectiondevices of the present embodiments may be combined into a grid to forman optical array, including a programmable optical array;

FIGS. 12 and 13, illustrate additional response shapes, in particular aFano resonance shape, which may be obtained using the presentembodiments;

FIG. 14 is a simplified schematic diagram showing a variation of thepresent embodiments in which Multiple Free-Spectral-Range (FSR) statesare achieved by placing one of the input ports at a different locationthan directly opposite the other input port;

FIG. 15 is a simplified schematic diagram showing a device according tothe present embodiments comprising three coupling regions and threeinjections waveguides and corresponding coupling points according toembodiments of the present invention;

FIGS. 16A to 16C and 17A to 17C are further configurations of the doubleinjection device of the present embodiments in which the Y-junction orother splitting element is eliminated and an independent referenceoptical field Eref is injected into one of the ports, together withgraphs showing the output responses;

FIGS. 18A to 18C are a configuration of the present embodiments andcorresponding graphs for phase modification and detection;

FIGS. 19A to 19F are an embodiment and corresponding graphs in which theoutput is responsive to variations in input optical power; and

FIGS. 20A to 20C and 21A to 21C are configurations and correspondinggraphs according to the present embodiments in which as with FIGS.19A-F, optical input power allows for changing between FSR states.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to aring-type resonator using double injection structures for responseshaping in frequency and time domains, and may include an opticalresponse shaper and/or a modulator device with multiple injection. Bythe term ‘response shaper’ is meant a device able to modify the timedependence and/or the spectral content or the phase of a given inputoptical signal. The device comprises a resonator having an enclosedgeometric structure, for example a ring or racetrack structure, at leasttwo injecting optical waveguides approaching the resonator to define atleast two coupling regions between the resonator and the injectingwaveguides, and defining at least two Free Spectral Range states. Thefree spectral range states may comprise a first, regular, state and atleast one additional larger period state. One or both of the couplingregions has a coupling coefficient selected for a predeterminedfrequency or time or phase response, and the coupling coefficient may bevariable in real time to render the response programmably variable.

The double injection (DI) device is modified in the present embodimentsto provide a range of responses by varying the coupling coefficients orother device parameters. That is to say a variable parameter doubleinjection device may be provided. A feature of certain embodiments ofthe DI design is that they comprise a single ring resonator, and requireone operating electrode for operation of the resonator. The operatingelectrode is not to be confused with the electrodes used for alteringthe device properties discussed. The use of a single operating electrodemay alleviate mismatch issues typically occurring in systems that dependon complementary devices (Class AB/B). Since only a single ring isrequired, the circuit is relatively simple to design and manufacture andthere are no cumulative fabrication variances, thus making the devicemuch less sensitive in most configurations. In terms of real-estate andpower consumption, this is also significant when considered in apractical receiver/transmitter setting incorporating arrays ofElectro-Optical (EO) elements on chip.

In the present embodiments there may be electrodes placed in thevicinity of the coupling regions to make the device dynamicallyprogrammable by altering conditions at the coupling regions. Even withthese electrodes in the vicinity of the coupling regions, the devicesmay be significantly simpler than other reported architectures.

Interestingly, the device provides most of its transmission responseswith a larger FSR than expected, that is to say typically twice that ofa conventional ring of the same size, without decreasing the perimeterof the resonator. This feature allows providing the same bandwidth,without increasing the required operational voltage, consequentlygenerating less heat, which further dissipates over a larger area.Despite being a resonance device, most of the transmissions obtained donot adhere to any critical coupling condition and hence variations inthe loss coefficient barely degrade the ER. Some transmissions howeverexhibit even higher sensitivity compared to single-pass devices (e.g.asymmetric MZI).

Shaping of the frequency response, or otherwise an electrical-to-opticalresponse, is demonstrated by means of a racetrack-shaped ring resonatordesigned and fabricated in a configuration referred to herein as theDouble Injection (DI) configuration. It will be appreciated that while aracetrack shape is shown, this is not essential to the presentembodiments and any continuous closed shape may be used. The DIconfiguration of the present embodiments possesses a property that itallows two Free Spectral Range states, namely the regular state and alarger e.g. double regular state (regular, 2×regular) to exist for asingle racetrack length.

Shaping in the present embodiments is realized by selecting differentcoupling coefficients that provide a variety of transmission shapes ortypes, as will be explained herein below. Specifically, the presentdisclosure demonstrates various shapes including: sinusoidal, triangular(linear), square (bandpass), dips and peaks (2 states), spikes(tangent-like), interleaver, fano-spectrum and a so-called, 20 dB-minParameters-Insensitive-Response modulator. The transmission types havebeen realized, fabricated in a silicon-on-insulator platform andcharacterized at wavelengths around 1,550 nm.

The present disclosure introduces various shaped responses obtained withthe DI resonator. In particular, an analysis in greater detail isprovided for one of the shapes: a Parameters-Insensitive-Response thatprovides an ER of at least 20 dB, referred to as PIR20. The variousresponses, differing in coupling coefficients, have been fabricatedusing silicon photonics technology and then characterizedexperimentally.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

Referring now to the drawings, FIG. 1 is a simplified schematic diagramshowing a Double injection resonator having dual FSR states. The DIresonator is embedded in a basic configuration as a passive structure.This configuration can attain 2 distinct FSR values with a singleresonator.

The underlying idea of the DI configuration is to inject at least two,mutually coherent, light signals of the same wavelength to a resonatorin pre-determined positions. A basic configuration according to oneembodiment of the present invention is described in FIG. 1. An inputwaveguide 1 is divided into two waveguides 2 and 2′ by means of aY-junction 10 or other splitting element. The junction 10 is designed todivide the input optical field in a suitable ratio: 50:50 or other,depending on the required functionality. Each of the two waveguides, 2,2′, hereinafter denominated Injecting waveguides, is configured so as toapproach the vicinity of the ring resonator at two respective locations3 and 3′, and to approach sufficiently close to allow coupling of theoptical guided field between the resonator and the Injecting waveguides.The corresponding two coupling coefficients are set to attainpredetermined transmission functionality between the input port 1 andthroughput port 4. The values of the coupling coefficients aredetermined either passively at the fabrication stage or actively byactuating a suitable physical effect, i.e. electrodes, that change thecoupling coefficients, using for example the electro-optic, thermo-opticor other light-control effect. Mathematically, the model describing theelectromagnetic field dependent on the wavelength for two injectingwaveguides is given by

$\begin{matrix}{{{E_{t\; 1}(\lambda)} = {{\frac{\left( {\tau_{1} - {\tau_{2}^{*}\alpha\; e^{{- i}\;\theta}}} \right)}{1 - {\tau_{1}^{*}\tau_{2}^{*}\alpha\; e^{{- i}\;\theta}}}{{E_{i\; 1}(\lambda)}}e^{{- i}\;\Phi_{i\; 1}}} - {\frac{\kappa_{1}\kappa_{2}^{*}\sqrt{\alpha}e^{{- i}\frac{\theta}{2}}}{1 - {\tau_{1}^{*}\tau_{2}^{*}\alpha\; e^{{- i}\;\theta}}}{{E_{i\; 2}(\lambda)}}e^{{- i}\;\Phi_{i\; 2}}}}},} & (1)\end{matrix}$where τ=|τ|e^(−iφτ), α, E_(i) and Φ_(i) are the transmission andcoupling coefficients of the directional couplers, the loss coefficientof the ring, injected fields and their phases, respectively. θ is thephase accumulated by the light traversing the ring at steady state

$\begin{matrix}{{{\theta(\lambda)} = {\frac{2\;\pi}{\lambda} \cdot {n_{eff}(\lambda)} \cdot L_{Ring}}},} & (2)\end{matrix}$with λ being the wavelength, L_(Ring) the perimeter of the ring andn_(eff) the effective index of the propagating mode. This model, appliedusually for a classical add-drop ring resonator model, can also describea classical notch resonator (E_(t2)=0, τ₂=1). The basic configuration,depicted in FIG. 1, inherently provides the ability to set electrodes inthe waveguides leading towards the resonator from the junction 10, theinput splitter via the so-called arms 2 and 2′. The electrodes may serveeither as phase calibration electrodes or signal modulating electrodes.FIG. 6, further discussed below, illustrates the basic DI configurationwith a possible electrode distribution. The electrodes may influencesome of the parameters, such as E_(i) and Φ_(i), of equation (1).

The DI resonator, if realized with no programming electrodes as shown inFIG. 1, or with electrodes that serve for tuning purposes only, may beoperated as a passive programmable waveform shaper or a multi-functionalfilter. If realized with electrodes that allow for variation in theresonator's phase or coupling coefficients in real time, then the resultmay serve for modulating an input signal in the time domain, so that theDI resonator acts as a modulator device. Depending on the type ofelectrodes and their purposes, the DI device may operate both as amodulator and programmable response shaper at the same time.

Configurations comprising DI resonators may include Multiple Injections(MI), for example triple injections, but at least two injections arerequired. Each injection may contribute an additional new FSR state andnaturally provide the ability to set an electrode over the correspondingarm. Since the injection relates to the resonator via a coupler, thenumber of free independent parameters increases while still using onlyone ring. The additional parameters may be selected to provide anadditional selection of useful response shapes as well as enhancingthose in the absence of the new injection. When designed inDouble-Injection, light at the throughput port can be regarded asconsisting of the combined contributions from two virtually, identical,add-drop ring resonators. The first ring is associated with input lightE_(i1) which is then emitted from the throughput port of this ring (i.e.the throughput port in FIG. 1); the second ring is associated with inputlight E_(i2) which is then emitted from the drop port of this ring(again the throughput port in FIG. 1). Thus, the left half portion ofthe second ring can be considered as a delay line of length L_(Ring)/2.

Note that the output transmission and the FSR of the DI resonator mayresemble that of a conventional ring when either E_(i1) or E_(i2) isvery small (the more conventional case), or when the first ring leanstowards critical coupling, i.e. α˜|τ₁/τ₂. In any other case, the delayline may dictate the FSR and transmission may be the result of thecontribution made by both virtual rings. The second virtual ring, whosedrop port is the relevant output for the DI resonator, does not have acritical coupling condition. It follows from the above discussion thatdevices based on DI design possess an exclusive property of being ableto operate in one of two FSR states, linked to either L_(Ring)/2 orL_(Ring), without modifying the length of the resonator. It is possibleto control the period of the first FSR state, linked to L_(Ring)/2, bypositioning the second injection (the lower injection in FIG. 1) nearbythe ring at a location that creates the required delay line. For thebasic configuration, where the position is exactly half of the ringperimeter, i.e. L_(Ring)/2, the common FSR formula for the larger FSR isthen given by

$\begin{matrix}{{{FSR}_{\lambda} = {2 \cdot \frac{\lambda^{2}}{N_{g}L_{Ring}}}},} & (3)\end{matrix}$where N_(g) is the refractive group index. This FSR, which is twice thevalue expected of a conventional ring, may also prove beneficial fordetection purposes as it inherently provides a larger operationalbandwidth.Response Shaping

Reference is now made to FIGS. 2A-2J which are a series of ten graphspresenting various response shapes of interest obtained using the DIresonator of FIG. 1 by choosing adequate coefficient values.

In FIGS. 2A-2D, the shapes are respectively triangular (linearized),square (bandpass), sinusoidal, and interleaver. The shapes in FIGS.2E-2G are respectively notch (2×FSR), peaks (2×FSR) and spikes(tangent-like). The shapes in FIGS. 2H-2J are respectively classicalnotch, classical peaks and Parameters-Insensitive-Response (PIR20).

Commercial software was used to simulate the circuit (via a steady-statemodel based on equation (1) above) and the waveguide dispersion,n_(eff)(λ), of the fundamental mode for a typical channel waveguide450×220 nm in silicon photonics. Common to all responses are theparameters: L_(Ring)=1,500 μm, φ_(τ,κ)=0° and |E_(in)|²=1 a.u.

The linearity of the response shape in FIG. 2A was analyzedtheoretically and revealed a high SFDR value of 132 dB with superiorperformance in the RF regime compared to RAMZI-based devices. In FIG.2D, a flat-top interleaver shape with passbands of 50 GHz at the −3 dBcorner points and cross-talk below −25 dB is shown. For a ring perimeterof 5,600 μm, the device can be characterized as a Nyquist interleaverwith a passband of 12.5 GHz at −3 dB and a −25 dB bandwidth of 19 GHz(−25 dB inter-channel isolation at 50% of the Nyquist frequency).Although its roll-off behavior is less sharp than of the recent RAMZIwork, the DI resonator footprint is half the size. It may be observedthat for the larger FSR notch and peaks shapes, as shown in FIGS. 2E and2F, the Q-factor is the same as that which a ring would have inconventional notch and add-drop configurations. In FIG. 2J a widebandattenuation response with a minimum ER of 20 dB is shown for threedifferent values of τ₁ and τ₂. The imbalance input power ratio (25%/75%)helps to decrease the sensitivity of the couplings value. Thisfunctionality is studied in greater detail hereinbelow. Note that forresponses presented in arbitrary units (a.u.), an average of 25 dB ER isobtained.

The shapes are realized by tailored coefficients α, τ₁, τ₂, E_(in). Thenotation |E_(ix)|²=P %|Φ^(o) indicates that P percent of the input powergoes to E_(ix), where φ^(o) is the phase of E_(ix) relative to E_(in).

Parameters-Insensitive Resonator/Modulator

Placing an electrical element, such as a PN diode, PIN diode, MOScapacitor or a solid-state transistor over the ring, but generallyexcluding coupler regions, converts the passive resonator into anelectro-optical modulator. A recent estimate in silicon photonics forbasic fabrication deviations, such as waveguide width, height, sidewallangle and cleaning artifacts, indicated about 15 nm deviation in thecoupling region. This may alter the splitting ratio of a directionalcoupler by more than 10% and directly impact the ER by several to a fewtens of decibels.

Reference is now made to FIG. 3A, which is a graph that shows theoptical output power as a function of an applied voltage for the PIR20device whose wavelength response is depicted in FIG. 2J. 2V is requiredto attain 20 dB attenuation; voltages between 2.0-4.4V will provide evenbetter than 20 dB of attenuation.

FIGS. 3B and 3C, respectively, present the ER of the PIR20 modulator anda cross-bar MZI modulator as a function of the couplers splitting ratio.The cross-bar configuration, which is typically realized by twodirectional couplers or multimode interference couplers, enjoy smallerfootprints and lower optical losses compared to a traditional Ycouplers-based MZI. In addition, the former couplers (if symmetrical)inherently differentiate the two signals by a π/2 phase, thus, avoidingthe need to bias the MZI with a short delay line or otherwise by a DC(direct current) electrode. To obtain a similar EO performance to thePIR20, the MZI arms were set to 1,000 μm (assuming a push-pullconfiguration), and a typical waveguide loss of 3 dB/cm has been assumedfor both devices.

In order to minimize the impact of fabrication deviations, so as toguarantee minimal ER value, the couplers of both devices may be designedto a central splitting ratio value. Such a design value may be at thecenter of the largest rectangle (w.r.t. FIGS. 3B and 3C) whose innerpoints provide a set of coupling values that yield at least the minimumattenuation. The rectangle size defines the parameters-insensitive rangeof the device. From FIGS. 3B and 3C, these central values are |τ₁₂|²=34%for the PIR20 resonator and |τ_(1,2)|²=50% for the MZI, when a minimalER of 20 dB is considered. It is evident from the figures that the“insensitivity” range of the PIR20 resonator is twice that of the MZIand safely covers the discussed range of potential fabricationvariances. Notice that for a conventional ring resonator, this range isless than 1% (see upper-right corner of FIG. 3B), i.e., a slightdeviation drastically degrades its ER. In general, the PIR20 resonatormay be sensitive to deviations of the input splitter, and the MZI tovariations in the arms, and such sensitivity may result in additionalphase deviation. In both cases, 3D simulations reveal that theabovementioned tolerances remain intact, i.e. |Δτ_(1,2)|²=Δ|E_(i1)|²=20%for the PIR20 as compared to |Δτ_(1,2)|²=ΔΦ_(arms)−10% for the MZI

As discussed, FIGS. 3A-3C show parameter-insensitivity of the device(PIR20) of FIG. 2J compared to an MZI. FIG. 3A shows the transmission ofthe PIR20 as a function of an applied voltage over a 1,400 μm MOScapacitor electrode. The voltage alters n_(Guide) (linearly for acapacitor) through the plasma dispersion effect (Δn_(Guide) of −4·10⁻⁴at 2V), consequently changing n_(eff). FIGS. 3B and 3C show ER value asa function of the couplers splitting ratio for the PIR20 and thecross-bar MZI modulators, respectively. The black dots 20 and 22 in thecenters of the rectangles 24 and 26 are the central splitting-ratiovalues which may be targeted in the design.

For applications requiring limited bandwidth, such as interleavers,filters or bandwidth-limited switches, the MZI arms may typically beimbalanced, that is in terms of length: thus for example the two armsmay be 1,000 μm and 1,900 μm for a 40 GHz Bandwidth. The added delayline, of length 900 μm, which creates an asymmetry in the losses betweenthe two arms, hardly degrades the insensitivity range. However,variations in the loss coefficient itself will affect the MZI morestrongly than the PIR20.

Quadrature Amplitude Modulation (QAM)

In the basic DI configuration, if electrodes are distributed to controlΦ_(i) and θ, it is possible to manipulate both the phase and amplitudeof the optical field emitted from the throughput port, to achieveadvanced signal constellations. Such signals are required in moderncommunication architectures such as, for example, Phase Shift Keying(PSK), Pulse Amplitude Modulation (PAM), Quadrature Amplitude modulation(QAM) and Amplitude and Phase Shift Keying (APSK). For QAM, or APSKsignal generation, placing electrodes over the DI resonator and upperarm, it is possible to control the optical field intensity and phase(from 0 to 2π). Since DI-based devices have a larger FSR state, thenumber of unique points within the pool of output points increaseproportionally to the FSR period. This property may reduce the errorbetween the required signal point and the available signal point(quantization noise), as more points are available for the sameresonator length. FIGS. 10A-10C show a possible configuration of aDI-based resonator operating at the larger FSR state and providing a QAMconstellation via twice the number of unique pool points.

Field Programmable Optical Array (FPOA) for Photonic Signal Processing.

It is possible to place electrodes over the input/ring couplers in orderto be able to fully reconfigure the couplers so as to generate variousresponse shapes. Such a device may then participate in a grid of devicesthat link to each other to produce the response of a single,parallel/serially chained device. Linking can be provided by input tooutput port connections or by direct coupling via proximity. Shaping ofthe response may be in the frequency domain as well as in the timedomain. In recent years, the research in this field of grids of opticaldevices has been accelerating as photonic processors are aimed atintegrating with, or replacing, their electrical counterparts. FIG. 11shows an illustration of a basic grid 110 that comprises DI devices 112according to the present embodiments such as example 114. Example 114includes first and second input ports 116 and 118 respectively, atunable coupler 120, 122, and 124, tunable phase shifters 126 and 128,and a racetrack resonator 130 with tunable electrodes 132 and 134, adrop port 136 and a throughput port 138. The devices 112 are connectedtogether in the grid 110 to form a photonic signal processor.

Results

Reference is now made to FIGS. 4A-4J through which are demonstrated thevarious transmission responses using silicon photonics technology. FIG.4D shows a Scanning Electron Microscope (SEM) view 12 of the completeoptical circuit and a zoom-in view 14 of the racetrack resonator andinput couplers. The spectral response of the devices around 1,550 nm(with resolution Δλ<0.05 nm) for the “TE” polarization is presented inFIG. 4A-J, in order of appearance corresponding to FIG. 2A-J. Moreparticularly, in FIGS. 4A-4C, the shapes are respectively triangular(linearized), square (bandpass), and sinusoidal. The shapes in FIGS.4E-4G are respectively notch (2×FSR), peaks (2×FSR) and spikes(tangent-like). The shapes in FIGS. 4H-4J are respectively classicalnotch, classical peaks and Parameters-Insensitive-Response (PIR20).

The racetrack perimeter is 477 μm and the average waveguide loss is 15dB/cm or α=0.921 (estimated by fitting α and τ to one of the dips in anotch resonator employing the same racetrack). The two obtained FSRvalues were 1.4 nm, and 2.8 nm.

Specifically, FIGS. 4A-J show a SEM image FIG. 4D and spectral responses(E_(t1)) of optical circuits comprising the DI resonator. Some plots arein normalized units (nu). FIGS. 4A-C in the 1^(st) row show shapes whichare respectively triangular, square and sinusoidal. FIGS. 4E-4G in the2^(nd) row show shapes which are a notch (2×FSR), peaks (2×FSR) andspikes (tangent-like). The 3^(rd) row shows FIGS. 4H-4J which are aclassical notch, classical peaks and Parameters-Insensitive-Response(PIR20). FIG. 4D shows views of the fabricated Double-Injection devicewith either input splitter components: standard Y coupler 14 (bottom) orDC coupler (12, middle), and a reference device of a simple add-dropracetrack resonator (16 upper).

FIGS. 4A-4J may confirm that devices based on the DI resonator canproduce a variety of response shapes by judicious selection of thecouplings and input coefficients while providing significant ER andbandwidth. Improved dynamic range may be attained if the coefficientsobtained in fabrication are close to theoretical coefficients. Due tocoupler dispersion and mismatch between design and fabrication, some ofthe transmissions exhibit better match to theory at wavelengths otherthan those intended, resulting in a certain spectral-shift.

In FIG. 4J, a PIR20 device with an intentional deviation in coupler τ₁(|τ₁|²=24% instead of |τ₁|²=34%) yields a wideband notch transmissionwith 20 dB of ER. This deviation falls within the insensitivity range ofthe device, thus, supporting the analysis presented earlier for thePIR20 resonator. Note that the enhanced ER was also attained at adeviation in the measured loss coefficient relative to the originaldesign (α=0.92 vs. α=0.99).

Discussion

A ring-type resonator designed in Double Injection configuration isshown to provide various response shapes by appropriately choosing thecoupling coefficients and input power ratio. An inherent feature of theDouble Injection configuration allows operation in two FSR states forthe same resonator length. The greater FSR, twice the conventionalvalue, can be utilized for obtaining wider operation bandwidth withlower power consumption in advanced transmission techniques. Some of theshapes presented include the triangular, rectangular, interleaver andthe parameters-insensitive response.

The values of the parameters required for the realization of eachresponse shape are significantly different from each other, thusavoiding unintended “roaming” among shapes, which may otherwise occurdue to deviations in, e.g., fabrication, temperature and electro-opticeffects. The obtained shapes are of practical relevance for various RFanalog and digital applications at the transmitter as well as thereceiver side.

The so-defined PIR20 modulator was analyzed and shown to be twice astolerant to parameter deviations compared to a conventional MZI andsignificantly more tolerant compared to a conventional ring modulator.Designed to attenuate at least 20 dB with extended bandwidth and lowoperation voltage (2V), makes it a viable candidate for large scaleintegration.

The response shapes described in theoretical section were experimentallydemonstrated by DI devices fabricated and characterized in an SOIplatform. The devices transmission exhibited good ER behavior as afunction of wavelength with similar shape and properties of theirtheoretical counterparts. In particular, a PIR20 device with anintentional deviation (10%) in one of the couplers, had provided anotch-like response with 20 dB ER, thus supporting the concept ofextended tolerance. The richness of the shapes demonstrated in thepresent embodiments is intended to confirm the practical significance ofthe Double Injection configuration.

Methods

Fabrication.

DI-based optical devices according to the present embodiments werefabricated. A Silicon-On-Insulator (SOI) substrate by SOITEC© was usedwith a 220 nm silicon layer lightly doped with Boron (1.3×10¹⁵ cm⁻³) anda 2 μm native oxide layer underneath. The design was patterned to thechip by Electron Beam Lithography (Raith150) with ZEP520 resist. It wasthen etched using a deep Reactive-Ion Etching process to completelyremove the silicon layer in order to form 450×220 nm channel waveguides.Finally, a 1 μm oxide layer was deposited on top by Plasma-enhancedChemical Vapor Deposition. Once ready, the chip was coated with astandard resist and diced to from a 1×1 cm square chip. In each corner afew devices, with tapered waveguides at the facet, could be approachedby external fibers (see FIG. 4D).

For responses requiring 50-50 input power splitting, a conventionalY-coupler (3 dB coupler) was employed to equally split the incominglight. For the square and sinusoidal shapes, a 90° phase difference isrequired. This was achieved by extending the lower arm by 110 nm toyield the proper phase. For such a short length, the added dispersionwas found to be negligible. For other splitting ratios, a DC unit wasplaced instead of the Y-coupler. From the input splitter, the twowaveguides continuing to the racetrack were curved, simulated anddesigned so as to deliver equal amplitudes and phases at entry. The dropport was not used, and thus the light continuing to the through port,i.e. Et_(t2), needed to be attenuated for suppressing re-coupling to theracetrack via reflections. This was realized by slowly narrowing thewaveguide width to zero over some distance (˜300 μm), thus allowing thepropagating mode to rapidly convert into radiation modes. Suchattenuating tapers were also placed in devices using a DC as an inputsplitter in order to suppress reflections.

Simulations.

The waveguide as produced in simulations had a trapezoidal cross sectionwith exponent-like decaying walls. To simulate the circuit and couplers,a waveguide with trapezoidal geometry and complementary error-function(Erfc) decay profile was employed. To reduce dispersion of directionalcouplers we chose to work with a short parallel section, L_(c)=5 μm. Thesimulations may account for the curved parts of the coupler(R_(curve)=10 μm), however, their contribution was observed to beinsignificant (around 1% of |τ|²).

Reference is now made to FIG. 5A, which is a SEM image showing thecross-section of the fabricated waveguide, the matched simulatedstructure and coupling profiles as a function of the DC gap andwavelength (dispersion). The gaps required for the various couplers usedin the devices, varied between 50 to 250 nm.

More specifically FIGS. 5A to 5D show a waveguide cross-section SEMimage and a simulated structure. FIG. 5A shows view of the trapezoidalcross-section for the parallel section of a DC. FIG. 5B shows anillustration of the structure simulated in the software to analyze thering/input couplers. FIG. 5C shows the simulated coupling coefficient asa function of the gap between the bus and ring waveguides (κ→powercoupled to the ring), and FIG. 5D shows the dispersion of a coupler forvarious lengths of parallel section.

FIG. 5D demonstrates the dispersion of the coupler for various couplinglengths. Even though a longer coupler results in larger dispersion, itis possible to find lengths that provide very small dispersion for anarrow bandwidth of the spectrum. This, however, will make the couplingchange more rapidly as a function of the gap, thus making it harder totarget specific values. Note that the dispersion, in this case, will begreater for the rest of the spectrum and the device footprint mayincrease. In general, the engineering and fabrication of a coupler foran optical circuit with specific needs, requires careful considerations.

Optical Measurements.

The spectral response of the optical devices was measured using anHP81689A tunable laser. The light propagated through PolarizationMaintaining fiber and butt coupled via an imaging system to the siliconwaveguide by a tapered fiber (2 μm spot size). Light coming from thechip was directed to an HP81637B photodetector. Both the laser and thephotodetector were modules installed on an HP8163A mainframe thatconnected to a PC computer via GPIB interface. Commercial measurementsoftware was used to control the equipment supporting the experiments.The setup was tuned for the “TE”-like (E_(x)>E_(y)) polarization and thefundamental mode was assumed to have been propagated in the device.

FIG. 6 is a simplified schematic diagram of a double injection deviceaccording to the present embodiments. FIG. 6 illustrates an exemplarydouble injection resonator 60 device according to the presentembodiments which 114 includes first and second input ports 116 and 118respectively, a tunable coupler 120, 122, and 124, tunable phaseshifters 126 and 128, and a racetrack resonator 130 with tunableelectrodes 132 and 134, a drop port 136 and a throughput port 138.

FIG. 7 shows a compact way to shape the Double-Injection (DI) resonatorbased-device 60 in order to obtain a smaller footprint of the DI device

FIG. 8 illustrates accessing of a drop port using a typical waveguidecrossing structure. If the drop port is required, a detector or anoutput coupler can be placed at the end of the port waveguide. However,another option can be attained using a waveguide crossing splitter toallow the light to continue further-on into the circuit:

The electrodes placed in the coupling region to make a programmabledevice, or at the ring waveguide may have thermo-optical properties. Anexample of that can be seen in the following figure:

FIG. 9 shows a DI device controlled by a thermal electrode 70 applyingthermo-Optical effect.

Referring now to FIGS. 10A to 10C, FIG. 10A is a diagram of a yetfurther double injection device and FIGS. 10B and 10C are graphs showingits use for QAM and these figures are discussed further hereinabove.FIG. 11 has likewise been discussed hereinabove.

Reference is briefly made to FIGS. 12 and 13, which illustrateadditional response shapes for optical devices having a single input.The so-called Fano resonance shape may be useful in such applications ashigh resolution sensors and ultra-low voltage modulators and switches.

Reference is now made to FIG. 14, which illustrates a variation in whichMultiple Free-Spectral-Range (FSR) is achieved by placing one of theinjections at a different location than directly opposite the secondone. In device 140 a first port 142 and a second port 144 are mutuallyoffset. Both couple to the racetrack resonator 146 as in the previousexamples. The output pattern emerges at throughput port 148. The newposition changes the length of the inherent delay line of the design,consequently, influencing on the FSR value. Thus, a device indouble-injection (DI) configuration can provide response shapes atvarious FSR values and is not limited to the conventional FSR ordouble-FSR. This is achieved without the need to change the perimeter ofthe ring. A necessary condition would be that the so-called partial FSRsand the conventional FSR have a common divisor. Thus the response shapemay be controlled by placing one of the injections at a location that isnot strictly opposite the other injection.

Response shaping may be viewed in the time domain. Assume having aperiodic electrical (voltage) wave in the time domain, and let thiselectrical wave drive the resonator electrode. Denote this as “inputsignal”. Also assume that a photo-diode is connected at the deviceoutput. A periodic electrical signal may be obtained at the diode outputhaving a different shape than the input signal.

The shape of the output signal can be modified by changing the voltagescontrolling other electrodes of the device. It is possible to performfrequency multiplication using this device.

Reference is now made to FIG. 15, which is a simplified diagramillustrating a device 150 for multiple—that is more than two—injection.Such multiple injection may be realized by adding additional couplingregions, thus providing more free parameters that can be used to shapethe device responses or otherwise to enhance those found with fewerinjections. Below is an example for triple injection in which threecoupling regions, 152, 154 and 156 are provided. All three lead tocouplings to racetrack 158 at different points. For the case of multipleinjections, the input splitter can be realized by a DC splitter or MMIsplitter. It is noted that the optical inputs need not be from a singleoptical source. The output shape emerges at throughput port 160

Reference is now made to FIGS. 16A, 16B and 16C, and also to 17A, 17Band 17C. In a further configuration of the double injection device, asshown at 162, the Y-junction or other splitting element is eliminatedand an independent reference optical field Eref is injected into one ofthe ports 164. Both are coupled to the racetrack 166 in the normal way.This field, alternatively denominated the control field, is intended toaffect the response of the input signal Ein coupled into the other port168 of DI device 162, in the frequency and/or time domain. In a possibleconfiguration, the reference optical field may replace a controlelectrical field and its corresponding actuating electrode, providing arealization of an all optical device. In other embodiments theapplication of both control fields, optical and electrical, may beadvantageous. The reference optical field may be generated close to theDI device, thus being a local oscillator, or at a remote location andmay have the same optical carrier frequency as the input signal or adifferent one. The amplitude, power, phase or frequency of theindependent reference optical signal may control the transmissionfunction of the signal as shown in FIGS. 16A-C and 17A-C.

The two devices of FIGS. 16A and 17A may have different fabricationparameters. Each device receives an input optical signal, Ein, and areference optical signal, Eref. Also the optical inputs for E_(in) andE_(ref) are swapped in one device with respect to the other. Thus indevice 170 in FIG. 17A, Input port 172 is the optical input for E_(ref)and input port 174 is the optical input port for E_(in). Both arecoupled to the racetrack resonator 176. Below each device are theoptical field 16B and 17B and intensity 16C and 17C, at the throughputport, as a function of the phase of the “Input Signal” E_(in).

Reference is now made to FIGS. 18A, 18B and 18C which illustrate anembodiments designed for phase detection. It is possible to detect thephase of the input signal (here: E_(in)=E_(i1)) and convert it tooptical field or intensity. The DI device can be configured to providethe functionality shown in the present embodiment. The output signalmagnitude (at the throughput port) is a function of the phase of theinput signal E_(in). Phase detection can be used at the receiver side todetect the phase of an incoming optical signal when using advancedtransmission techniques, such as QAM, PSK and APSK. Specifically, asignal at port 180 and a reference signal at port 182 are injected to DIcircuit 184. The ports are coupled to racetrack 186 and the outputemerges at output port 188. The plots in FIGS. 18B and 18C show thefield magnitude and intensity responses as a function of the phase orthe input signal.

Reference is now made to FIGS. 19A-19F, which illustrate an embodimentencompassing response shape via optical power, that is to say a responseshape that is governed by the reference (CONTROL) optical power. It ispossible to obtain the different shapes shown in FIGS. 19B-F, and inparticular switch between responses, by changing the input optical powerinjected to device 190 at the optical control line, E_(control) 192. Theinput signal is injected at port 194 and both input and control linesare coupled to racetrack 196. The output emerges from throughput port198. Thus, in device 190, the optical input at E_(i2), serves as asignal input.

FIGS. 19B-19F indicate various responses of the DI resonator 190 thatmay be generated without modifying any parameters of the circuit expectthe input power of the control line. In the figures, the X-axisrepresents the frequency of both input ports. Switching may be carriedout between responses by suitable manipulation of the input power.

Reference is now made to FIGS. 20A-20C and FIGS. 21A-21C, whichillustrate control of FSR Shape via optical power, that is via opticalinput power. In this example, moving between two FSRs is carried outusing a different set of device parameters.

It is possible to move from one FSR state to another state by changingthe power of the optical control line. In FIG. 20A, in device 200, theoptical input 202 at E_(i1) serves as the control line, and the opticalinput at 204 is the signal line. Both are coupled to the racetrackresonator 206 and the output emerges at throughput port 208. In FIG.21A, in device 210, the optical input 212 at E_(i2), serves as thecontrol line and the optical input at 214 is the signal line. Both arecoupled to the racetrack resonator 216 and the output emerges atthroughput port 218. More particularly, FIG. 20A is a schematicdescription of inputting a signal and a control to the DI circuit tochange between FSR states.

In FIGS. 20B-20C, the switching FSR state of the Peak response shapes isshown and in FIGS. 21B and 21C, the switching FSR state of the Notchresponse shape is shown.

It is expected that during the life of a patent maturing from thisapplication many relevant modulators and ring-type configurations willbe developed and the scopes of the corresponding terms are intended toinclude all such new technologies a priori.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment, and the text is to beconstrued as if such a single embodiment is explicitly written out indetail. Conversely, various features of the invention, which are, forbrevity, described in the context of a single embodiment, may also beprovided separately or in any suitable subcombination or as suitable inany other described embodiment of the invention, and the text is to beconstrued as if such separate embodiments or subcombinations areexplicitly set forth herein in detail.

Certain features described in the context of various embodiments are notto be considered essential features of those embodiments, unless theembodiment is inoperative without those elements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting. In addition, any priority document(s) of this applicationis/are hereby incorporated herein by reference in its/their entirety.

What is claimed is:
 1. An optical response shaper and/or a modulatordevice with multiple injection, the device comprising: a resonatorhaving an enclosed geometric structure; at least two injection opticalwaveguides between an input port and a second end, the opticalwaveguides approaching the resonator at respective approach points;coupling regions between said resonator and said injecting waveguides atsaid approach points respectively, the coupling regions providingoptical coupling between said resonator and said injecting waveguides,the coupling regions being configured to inject at least two, mutuallycoherent light signals of the same wavelength to said resonator atpre-determined positions, the signals being injected in a samerotational sense; and an output port at a second end of one of saidinjection optical waveguides for providing a plurality of shapes offrequency or time or phase or intensity responses according toparameters of said injecting waveguides or of said coupling regions,wherein parameters of the coupling regions or the waveguides define atleast first and second Free Spectral Range states, and said first andsecond free spectral range states comprise a first, regular, state andan additional, different period state.
 2. The optical response shaper ofclaim 1, wherein at least one of said two coupling regions is configuredwith a coupling coefficient selected for said predetermined frequency ortime or phase response.
 3. The device of claim 2, further comprising atleast one electrode placed at the vicinity of at least one of saidcoupling regions, said additional electrode being for programmablyaltering a respective coupling coefficient to vary said predeterminedfrequency response or time response.
 4. The device of claim 3,comprising an electrode over each coupling region respectively, therebyto alter coupling coefficients at each coupling region.
 5. The device ofclaim 1, comprising one input port and a y-coupler to each of saidinjection waveguides.
 6. The device of claim 1, wherein each of said atleast two injection waveguides comprises a respective coupling region.7. The device of claim 6, wherein a length along a first of saidinjection waveguides from a respective input port to a respectivecoupling region is different from a length of a second of said injectionwaveguides from a respective input port to a respective coupling region.8. The device of claim 1, wherein the enclosed geometric structurecomprises a ring structure or a racetrack structure.
 9. The device ofclaim 1, comprising an electrode over one of said coupling regions, theelectrode comprising one member of the group comprising a PN diode, PINdiode, MOS capacitor, a BJT transistor, an electrode that usesthermo-optic effect, and an electrode that uses the electro-opticeffect.
 10. The device of claim 1, comprising an electrical element overat least one of said waveguides or waveguide conforming said resonator.11. The device of claim 1, wherein said predetermined response is onemember of the group consisting of sinusoidal, triangular, square,combined dips and peaks, spikes, an interleaver, a fano-spectrum shapeand a Parameters-Insensitive-Response.
 12. The device of claim 1 whereinsaid coupling coefficient is at least partly governed by a distancebetween said resonator and a respective waveguide or by the saidwaveguides' width, at a respective coupling region.
 13. The device ofclaim 1, configured to provide a constellation of points for quadratureamplitude modulation (QAM).
 14. The device of claim 1, configured toprovide one member of the group of modulations consisting of: PhaseShift Keying (PSK), Pulse Amplitude Modulation (PAM), QuadratureAmplitude Modulation (QAM) and Amplitude and Phase Shift Keying (APSK).15. The device of claim 1, wherein said time or frequency or phaseresponse is affected by an optical input power.
 16. The device of claim1, comprising only one resonator and only one operating electrode forcontrolling a resonance condition in said device.
 17. A fieldprogrammable optical array comprising optical devices according to claim1 connected together into a grid.
 18. A photonic signal processorcomprising a plurality of the device of claim 1, connected together in agrid.
 19. An optical response shaper and/or a modulator device withmultiple injection, the device comprising: a resonator having anenclosed geometric structure; at least two injection optical waveguidesbetween an input port and a second end, the optical waveguidesapproaching the resonator at respective approach points; couplingregions between said resonator and said injecting waveguides at saidapproach points respectively, the coupling regions providing opticalcoupling between said resonator and said injecting waveguides, thecoupling regions being configured to inject at least two, mutuallycoherent light signals of the same wavelength to said resonator atpre-determined positions, the light signals being injected in a samerotational sense, parameters of the coupling regions or the waveguidesdefining at least first and second Free Spectral Range states; and anoutput port at a second end of one of said injection optical waveguidesfor providing frequency or time or phase or intensity responsesaccording to said parameters of the injecting waveguides or of thecoupling regions.